Summary:
This runs a benchmark for LevelDB similar to what we have
in tools/run_flash_bench.sh. It requires changes to db_bench that I published
in a LevelDB fork on github. Some results are at:
http://smalldatum.blogspot.com/2015/04/comparing-leveldb-and-rocksdb-take-2.html
Sample output:
ops/sec mb/sec usec/op avg p50 Test
525 16.4 1904.5 1904.5 111.0 fillseq.v32768
75187 15.5 13.3 13.3 4.4 fillseq.v200
28328 5.8 35.3 35.3 4.7 overwrite.t1.s0
175438 0.0 5.7 5.7 4.4 readrandom.t1
28490 5.9 35.1 35.1 4.7 overwrite.t1.s0
121951 0.0 8.2 8.2 5.7 readwhilewriting.t1
Task ID: #
Blame Rev:
Test Plan:
Revert Plan:
Database Impact:
Memcache Impact:
Other Notes:
EImportant:
- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -
Reviewers: igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D37749
Summary:
This is done to avoid having each thread use the same seed between runs
of db_bench. Without this we can inflate the OS filesystem cache hit rate on
reads for read heavy tests and generally see the same key sequences get generated
between teste runs.
Task ID: #
Blame Rev:
Test Plan:
Revert Plan:
Database Impact:
Memcache Impact:
Other Notes:
EImportant:
- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -
Reviewers: igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D37563
Summary:
This adds:
1) use of --level_compaction_dynamic_level_bytes=true
2) use of --bytes_per_sync=2M
The second is a big win for disks. The first helps in general.
This also adds a new test, fillseq with 32kb values to increase the peak
ingest and make it more likely that storage limits throughput.
Sample outpout from the first 3 tests - https://gist.github.com/mdcallag/e793bd3038e367b05d6f
Task ID: #
Blame Rev:
Test Plan:
Revert Plan:
Database Impact:
Memcache Impact:
Other Notes:
EImportant:
- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -
Reviewers: igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D37509
Summary:
This changes loads to use vector memtable and disable the WAL. This also
increases the chance we will see IO bottlenecks during loads which is good to stress
test HW. But I also think it is a good way to load data quickly as this is a bulk
operation and the WAL isn't needed.
The two numbers below are the MB/sec rates for fillseq, bulkload using a skiplist
or vector memtable and the WAL enabled or disabled. There is a big benefit from
using the vector memtable and WAL disabled. Alas there is also a perf bug in
the use of std::sort for ordered input when the vector is flushed. Task is open
for that.
112, 66 - skiplist with wal
250, 116 - skiplist without wal
110, 108 - vector with wal
232, 370 - vector without wal
Task ID: #
Blame Rev:
Test Plan:
Revert Plan:
Database Impact:
Memcache Impact:
Other Notes:
EImportant:
- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -
Reviewers: igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D36957
Summary: Add a script, which checks out changes from a list of tags, build them and load the same data into it. In the last, checkout the target build and make sure it can successfully open DB and read all the data. It is implemented through ldb tool, because ldb tool is available from all previous builds so that we don't have to cross build anything.
Test Plan: Run the script.
Reviewers: yhchiang, rven, anthony, kradhakrishnan, igor
Reviewed By: igor
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D36639
Summary:
This adds p99.9 and p99.99 response times to the benchmark report and
adds a second report, report2.txt that has tests listed in test order rather
than the time in which they were run, so overwrite tests are listed for
all thread counts, then update etc.
Also changes fillseq to compress all levels to avoid write-amp from rewriting
uncompressed files when they reach the first level to compress.
Increase max_write_buffer_number to avoid stalls during fillseq and make
max_background_flushes agree with max_write_buffer_number.
See https://gist.github.com/mdcallag/297ff4316a25cb2988f7 for an example
of the new report (report2.txt)
Task ID: #
Blame Rev:
Test Plan:
Revert Plan:
Database Impact:
Memcache Impact:
Other Notes:
EImportant:
- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -
Reviewers: igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D36537
Summary:
The --stats_interval_seconds determines interval for stats reporting
and overrides --stats_interval when set. I also changed tools/benchmark.sh
to report stats every 60 seconds so I can avoid trying to figure out a
good value for --stats_interval per test and per storage device.
Task ID: #6631621
Blame Rev:
Test Plan:
run tools/run_flash_bench, look at output
Revert Plan:
Database Impact:
Memcache Impact:
Other Notes:
EImportant:
- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -
Reviewers: igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D36189
Summary:
This makes run_flash_bench.sh configurable. Previously it was hardwired for 1B keys and tests
ran for 12 hours each. That kept me from using it. This makes it configuable, adds more tests,
makes the duration per-test configurable and refactors the test scripts.
Adds the seekrandomwhilemerging test to db_bench which is the same as seekrandomwhilewriting except
the writer thread does Merge rather than Put.
Forces the stall-time column in compaction IO stats to use a fixed format (H:M:S) which makes
it easier to scrape and parse. Also adds an option to AppendHumanMicros to force a fixed format.
Sometimes automation and humans want different format.
Calls thread->stats.AddBytes(bytes); in db_bench for more tests to get the MB/sec summary
stats in the output at test end.
Adds the average ingest rate to compaction IO stats. Output now looks like:
https://gist.github.com/mdcallag/2bd64d18be1b93adc494
More information on the benchmark output is at https://gist.github.com/mdcallag/db43a58bd5ac624f01e1
For benchmark.sh changes default RocksDB configuration to reduce stalls:
* min_level_to_compress from 2 to 3
* hard_rate_limit from 2 to 3
* max_grandparent_overlap_factor and max_bytes_for_level_multiplier from 10 to 8
* L0 file count triggers from 4,8,12 to 4,12,20 for (start,stall,stop)
Task ID: #6596829
Blame Rev:
Test Plan:
run tools/run_flash_bench.sh
Revert Plan:
Database Impact:
Memcache Impact:
Other Notes:
EImportant:
- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -
Reviewers: igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D36075
Summary:
Whenever we add new tests in db_sanity_test.cc, the verification test
will fail since the old version db_sanity_test.cc does not have the
newly added test. This patch makes auto_sanity_test.sh always use
the db_sanity_test.cc of the newer commit.
As a result, a macro guard is added to allow db_sanity_test.cc to be
backward compatible.
Test Plan: tools/auto_sanity_check.sh
Reviewers: sdong, rven, igor
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D35997
Summary:
This is like readwhilewriting but uses Merge rather than Put in the writer thread.
I am using it for in-progress benchmarks. I don't think the other benchmarks for Merge
cover this behavior. The purpose for this test is to measure read performance when
readers might have to merge results. This will also benefit from work-in-progress
to add skewed key generation.
Task ID: #
Blame Rev:
Test Plan:
Revert Plan:
Database Impact:
Memcache Impact:
Other Notes:
EImportant:
- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -
Reviewers: igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D35115
Summary:
Our existing test notation is very similar to what is used in gtest. It makes it easy to adopt what is different.
In this diff I modify existing [[ https://code.google.com/p/googletest/wiki/Primer#Test_Fixtures:_Using_the_Same_Data_Configuration_for_Multiple_Te | test fixture ]] classes to inherit from `testing::Test`. Also for unit tests that use fixture class, `TEST` is replaced with `TEST_F` as required in gtest.
There are several custom `main` functions in our existing tests. To make this transition easier, I modify all `main` functions to fallow gtest notation. But eventually we can remove them and use implementation of `main` that gtest provides.
```lang=bash
% cat ~/transform
#!/bin/sh
files=$(git ls-files '*test\.cc')
for file in $files
do
if grep -q "rocksdb::test::RunAllTests()" $file
then
if grep -Eq '^class \w+Test {' $file
then
perl -pi -e 's/^(class \w+Test) {/${1}: public testing::Test {/g' $file
perl -pi -e 's/^(TEST)/${1}_F/g' $file
fi
perl -pi -e 's/(int main.*\{)/${1}::testing::InitGoogleTest(&argc, argv);/g' $file
perl -pi -e 's/rocksdb::test::RunAllTests/RUN_ALL_TESTS/g' $file
fi
done
% sh ~/transform
% make format
```
Second iteration of this diff contains only scripted changes.
Third iteration contains manual changes to fix last errors and make it compilable.
Test Plan:
Build and notice no errors.
```lang=bash
% USE_CLANG=1 make check -j55
```
Tests are still testing.
Reviewers: meyering, sdong, rven, igor
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D35157
Summary:
gtest does not use exceptions to fail a unit test by design, and `ASSERT*`s are implemented using `return`. As a consequence we cannot use `ASSERT*` in a function that does not return `void` value ([[ https://code.google.com/p/googletest/wiki/AdvancedGuide#Assertion_Placement | 1]]), and have to fix our existing code. This diff does this in a generic way, with no manual changes.
In order to detect all existing `ASSERT*` that are used in functions that doesn't return void value, I change the code to generate compile errors for such cases.
In `util/testharness.h` I defined `EXPECT*` assertions, the same way as `ASSERT*`, and redefined `ASSERT*` to return `void`. Then executed:
```lang=bash
% USE_CLANG=1 make all -j55 -k 2> build.log
% perl -naF: -e 'print "-- -number=".$F[1]." ".$F[0]."\n" if /: error:/' \
build.log | xargs -L 1 perl -spi -e 's/ASSERT/EXPECT/g if $. == $number'
% make format
```
After that I reverted back change to `ASSERT*` in `util/testharness.h`. But preserved introduced `EXPECT*`, which is the same as `ASSERT*`. This will be deleted once switched to gtest.
This diff is independent and contains manual changes only in `util/testharness.h`.
Test Plan:
Make sure all tests are passing.
```lang=bash
% USE_CLANG=1 make check
```
Reviewers: igor, lgalanis, sdong, yufei.zhu, rven, meyering
Reviewed By: meyering
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D33333
Summary:
Without this change about half of the updaterandom reads and merge puts will be for keys that don't exist.
I think it is better for these tests to start with a full database and use fillseq to fill it.
Task ID: #
Blame Rev:
Test Plan:
Revert Plan:
Database Impact:
Memcache Impact:
Other Notes:
EImportant:
- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -
Reviewers: igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D35043
Summary:
Single threaded tests -> sync=0 Multi threaded tests -> sync=1 by default unless DB_BENCH_NO_SYNC is defined.
Also added updaterandom and mergerandom with putOperator. I am waiting for some results from udb on this.
Test Plan:
DB_BENCH_NO_SYNC=1 WAL_DIR=/tmp OUTPUT_DIR=/tmp/b DB_DIR=/tmp ./tools/benchmark.sh debug,bulkload,fillseq,overwrite,filluniquerandom,readrandom,readwhilewriting,updaterandom,mergerandom
WAL_DIR=/tmp OUTPUT_DIR=/tmp/b DB_DIR=/tmp ./tools/benchmark.sh debug,bulkload,fillseq,overwrite,filluniquerandom,readrandom,readwhilewriting,updaterandom,mergerandom
Verify sync settings
Reviewers: sdong, MarkCallaghan, igor, rven
Reviewed By: igor, rven
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D34185
Summary:
When using latest clang (3.6 or 3.7/trunck) rocksdb is failing with many errors. Almost all of them are missing override errors. This diff adds missing override keyword. No manual changes.
Prerequisites: bear and clang 3.5 build with extra tools
```lang=bash
% USE_CLANG=1 bear make all # generate a compilation database http://clang.llvm.org/docs/JSONCompilationDatabase.html
% clang-modernize -p . -include . -add-override
% make format
```
Test Plan:
Make sure all tests are passing.
```lang=bash
% #Use default fb code clang.
% make check
```
Verify less error and no missing override errors.
```lang=bash
% # Have trunk clang present in path.
% ROCKSDB_NO_FBCODE=1 CC=clang CXX=clang++ make
```
Reviewers: igor, kradhakrishnan, rven, meyering, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D34077
Summary:
This diff contains trivial fixes for 6 scan-build warnings:
**db/c_test.c**
`db` variable is never read. Removed assignment.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-9b77d2.html#EndPath
**db/db_iter.cc**
`skipping` local variable is assigned to false. Then in the next switch block the only "non return" case assign `skipping` to true, the rest cases don't use it and all do return.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-13fca7.html#EndPath
**db/log_reader.cc**
In `bool Reader::SkipToInitialBlock()` `offset_in_block` local variable is assigned to 0 `if (offset_in_block > kBlockSize - 6)` and then never used. Removed the assignment and renamed it to `initial_offset_in_block` to avoid confusion.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-a618dd.html#EndPath
In `bool Reader::ReadRecord(Slice* record, std::string* scratch)` local variable `in_fragmented_record` in switch case `kFullType` block is assigned to false and then does `return` without use. In the other switch case `kFirstType` block the same `in_fragmented_record` is assigned to false, but later assigned to true without prior use. Removed assignment for both cases.
scan-build reprots:
http://home.fburl.com/~sugak/latest20/report-bb86b0.html#EndPathhttp://home.fburl.com/~sugak/latest20/report-a975be.html#EndPath
**table/plain_table_key_coding.cc**
Local variable `user_key_size` is assigned when declared. But then in both places where it is used assigned to `static_cast<uint32_t>(key.size() - 8)`. Changed to initialize the variable to the proper value in declaration.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-9e6b86.html#EndPath
**tools/db_stress.cc**
Missing `break` in switch case block. This seems to be a bug. Added missing `break`.
Test Plan:
Make sure all tests are passing and scan-build does not report 'Dead assignment' and 'Dead initialization' bugs.
```lang=bash
% make check
% make analyze
```
Reviewers: meyering, igor, kradhakrishnan, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D33795
Summary: rockuse more memory that asked to. Monitor and report.
Test Plan: run the pro with conditions to simulate the overusage. It should report that the process is using more memory than needed.
Reviewers: yhchiang, rven, sdong, igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D33249
Summary: We don't have plans to work on this in the short term. If we ever resurrect the project, we can find the code in the history. No need for it to linger around
Test Plan: no test
Reviewers: yhchiang, rven, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D32349
Summary:
This diff adds BlockBasedTable format_version = 2. New format version brings better compressed block format for these compressions:
1) Zlib -- encode decompressed size in compressed block header
2) BZip2 -- encode decompressed size in compressed block header
3) LZ4 and LZ4HC -- instead of doing memcpy of size_t encode size as varint32. memcpy is very bad because the DB is not portable accross big/little endian machines or even platforms where size_t might be 8 or 4 bytes.
It does not affect format for snappy.
If you write a new database with format_version = 2, it will not be readable by RocksDB versions before 3.10. DB::Open() will return corruption in that case.
Test Plan:
Added a new test in db_test.
I will also run db_bench and verify VSIZE when block_cache == 1GB
Reviewers: yhchiang, rven, MarkCallaghan, dhruba, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D31461
Summary:
A command line like this to run all the tests:
source benchmark.config.sh && nohup ./benchmark.sh 'bulkload,fillseq,overwrite,filluniquerandom,readrandom,readwhilewriting'
where
benchmark.config.sh is:
export DB_DIR=/data/mysql/rocksdata
export WAL_DIR=/txlogs/rockswal
export OUTPUT_DIR=/root/rocks_benchmarking/output
Will fail for the tests that need a new DB .
Also 1) set disable_data_sync=0 and 2) add debug mode to run through all the tests more quickly
Test Plan: run ./benchmark.sh 'debug,bulkload,fillseq,overwrite,filluniquerandom,readrandom,readwhilewriting' and verify that there are no complaints about WAL dir not being empty.
Reviewers: sdong, yhchiang, rven, igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D30909
Summary:
Priliminary diff to solicit comments.
Given DB path, dump all SST files (key/value and properties), WAL file and manifest
files. What command options do we need to support for this command? Maybe
output_hex for keys?
Test Plan: Create additional ldb unit tests.
Reviewers: sdong, rven
Reviewed By: rven
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D29547
Summary: as title
Test Plan: ran it
Reviewers: yhchiang, igor, sdong, MarkCallaghan
Reviewed By: MarkCallaghan
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D25563
Summary:
Fix the following compile warning in db_stress.cc on Mac
tools/db_stress.cc:1688:52: error: format specifies type 'unsigned long' but the argument has type '::google::uint64' (aka 'unsigned long long') [-Werror,-Wformat]
fprintf(stdout, "DB-write-buffer-size: %lu\n", FLAGS_db_write_buffer_size);
~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~~
%llu
Test Plan:
make
Summary:
Introduces a new class for managing write buffer memory across column
families. We supplement ColumnFamilyOptions::write_buffer_size with
ColumnFamilyOptions::write_buffer, a shared pointer to a WriteBuffer
instance that enforces memory limits before flushing out to disk.
Test Plan: Added SharedWriteBuffer unit test to db_test.cc
Reviewers: sdong, rven, ljin, igor
Reviewed By: igor
Subscribers: tnovak, yhchiang, dhruba, xjin, MarkCallaghan, yoshinorim
Differential Revision: https://reviews.facebook.net/D22581
Summary:
In some environment such as android, the c++ library does not have
std::to_string. This path adds rocksdb::ToString(), which wraps std::to_string
when std::to_string is not available, and implements std::to_string
in the other case.
Test Plan:
make dbg -j32
./db_test
make clean
make dbg OPT=-DOS_ANDROID -j32
./db_test
Reviewers: ljin, sdong, igor
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D29181
Summary: First commit for rdb shell
Test Plan: unit_test.js does simple assertions on most of the main functionality; will update with rest of tests
Reviewers: igor, rven, lijn, yhciang, sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D28749
Summary:
Make db_stress built for ROCKSDB_LITE.
The test doesn't pass tough. It seg fault quickly. But I took a look and it doesn't seem to be related to lite version. Likely to be a bug inside RocksDB.
Test Plan: make db_stress
Reviewers: yhchiang, rven, ljin, igor
Reviewed By: igor
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D28797
Summary:
We need to turn on -Wshorten-64-to-32 for mobile. See D1671432 (internal phabricator) for details.
This diff turns on the warning flag and fixes all the errors. There were also some interesting errors that I might call bugs, especially in plain table. Going forward, I think it makes sense to have this flag turned on and be very very careful when converting 64-bit to 32-bit variables.
Test Plan: compiles
Reviewers: ljin, rven, yhchiang, sdong
Reviewed By: yhchiang
Subscribers: bobbaldwin, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D28689
Summary:
Refactor sst_dump to follow the same structure as ldb. Introduce a
SSTDump interface.
Test Plan: built sst_dump and tried it manually.
Reviewers: sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D28485
Summary: Previously I made `make check` work with -Wshadow, but there are some tools that are not compiled using `make check`.
Test Plan: make all
Reviewers: yhchiang, rven, ljin, sdong
Reviewed By: ljin, sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D28497
Summary: as title
Test Plan: ./db_test
Reviewers: sdong, yhchiang, rven, igor
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D28269
Summary: Fix lint errors and coding style of ldb related codes.
Test Plan: ./ldb
Reviewers: ljin, sdong, igor
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D28125
Summary:
Added two flags which operate as follows:
in_place_update: enable in_place_update for default column family
set_in_place_one_in: toggles the value of the option inplace_update_support with a probability of 1/N
Test Plan:
Run db_stress with the two flags above set.
Specifically tried in_place_update set to true and set_in_place_one_in set to 10,000.
Reviewers: ljin, igor, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D28029
Summary: RocksDB already depends on C++11, so we might as well all the goodness that C++11 provides. This means that we don't need AtomicPointer anymore. The less things in port/, the easier it will be to port to other platforms.
Test Plan: make check + careful visual review verifying that NoBarried got memory_order_relaxed, while Acquire/Release methods got memory_order_acquire and memory_order_release
Reviewers: rven, yhchiang, ljin, sdong
Reviewed By: ljin
Subscribers: leveldb
Differential Revision: https://reviews.facebook.net/D27543
Summary: Allow SetOptions() during db_stress test
Test Plan: make crash_test
Reviewers: sdong, yhchiang, rven, igor
Reviewed By: igor
Subscribers: leveldb
Differential Revision: https://reviews.facebook.net/D25497
Summary: Try to match some parameters from Dhruba's benchmarks on github
Test Plan: ran it
Reviewers: sdong, yhchiang, igor
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D24687
Summary: Those were introduced with 2fb1fea30f because the flushing behavior changed when max_background_flushes is > 0.
Test Plan: make check
Reviewers: ljin, yhchiang, sdong
Reviewed By: sdong
Subscribers: leveldb
Differential Revision: https://reviews.facebook.net/D23577
Summary:
Hope these scripts will allow people to run/repro benchmark easily
I think it is time to re-run flash benchmarks and report results
Please comment if any other benchmark runs are needed
Test Plan: ran it
Reviewers: yhchiang, igor, sdong
Reviewed By: igor
Subscribers: dhruba, MarkCallaghan, leveldb
Differential Revision: https://reviews.facebook.net/D23139
Summary:
The compilers we use treat char as signed. However, this is not guarantee of C standard and some compilers (for ARM platform for example), treat char as unsigned. Code that assumes that char is either signed or unsigned is wrong.
This change explicitly casts the char to signed version. This will not break any of our use cases on x86, which, I believe are all of them. In case somebody out there is using RocksDB on ARM AND using bloom filters, they're going to have a bad time. However, it is very unlikely that this is the case.
Test Plan: sanity test with previous commit (with new sanity test)
Reviewers: yhchiang, ljin, sdong
Reviewed By: ljin
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D22767
